Acoustic guitars have been used for centuries and generally weigh less than 2.25 kg (5 lbs). Acoustic guitars are frequently played seated, while standing with a riser under one foot to support the guitar on a raised leg, or while using a stand for the instrument.
Electric guitars, in contrast, have been used for only the past 60 years. Most electric guitars weigh between 2.75 kg (6 lbs) and 4.5 kg (10 lbs). Despite their increased weight, most guitarists play electric guitars in a standing position with the electric guitar supported by a strap slung over a shoulder of the guitarist.
The combination of the increased weight of an electronic guitar and the standing playing position increases ergonomic stress on the guitarist, particularly the guitarist's joints. Ergonomic stress can cause or exacerbate chronic joint problems and can cause a guitarist to be unable to play, in extreme cases. Various attempts have been made to make an ergonomic guitar but none have been successful at making a comfortable guitar, especially for smaller guitarists.
Some prior art guitars attempt to reduce stress on the joints of the guitarist by reducing the size of the body and using a standard-sized neck, thus reducing weight. In extreme examples, the body of this style of prior art guitar can be nearly as narrow as its neck, providing a stick-like appearance. As a result of the reduced weight in their body, these prior art guitars require the guitarist to use their right wrist to anchor the guitar because they are unbalanced. This prevents elbow-driven strumming altogether and also prevents relaxing the wrist during wrist-driven strumming.
Other prior art guitars reduce weight by carving out chambers in the body of the guitar or by using lighter materials. While reducing weight, these attempts disrupt the balance, change the natural sound of the guitar, and require the guitarist to use their left wrist or right wrist to anchor the guitar.
Yet another attempt to produce an ergonomic guitar involves twisting the neck of the guitar around its longitudinal axis. This reduces, but does not eliminate, stress on a guitarist's left wrist but, in guitars where chords and string-bending are used, twisting can result in the strings buzzing when they strike higher frets in the rotated plane.
Some other prior art guitars have attempted to improve ergonomics in the left shoulder and elbow by reducing the scale length of the guitar's neck. Standard scale lengths vary between 60.96 cm (24 in) and 66.04 cm (26 in), with the majority of electric guitars falling between 62.865 cm (24.75 in) and 64.77 cm (25.5 in), whereas some reduced scale-length guitars have scale lengths between 52.7 cm (20.75 in) and 57.15 cm (22.5 in). This helps to compensate for the balance issues but makes fingering the neck difficult, particularly for adults. Unfortunately, while less left shoulder and left elbow stress may occur, shorter scale lengths increase the stress on the left hand when playing chords due to the closer-spaced frets. Further, reduced scale-length guitars exhibit less-stable intonation and weaker tone, as compared to standard scale-length guitars.
Another prior-art solution to improve balance is relocating the tuners from the headstock of the prior art guitar to the bridge. While this solution can improve balance by bringing weight from the neck to the body of the guitar, it requires alternate methods of fastening and tightening the strings which, in turn, requires non-standard strings and prevents the guitarist from plucking strings with a plucking hand and tuning with the chording hand.
Short-scale guitars and similar instruments, such as ukuleles and mandolins, do not have the same ergonomic difficulties as conventional scale-length guitars because their neck is shorter than a conventional scale-length guitar and, thus, are more balanced.
Longer scale-length bass guitars do not have the same ergonomic challenges because they are generally picked or plucked and not strummed. This playing style allows the picking or plucking hand to be stationary and further support the instrument.